The concept of an alpha voltaic battery was proposed in 1954 as disclosed in W. G. Pfann and W. van Roosbroeck, Journal of Applied Physics, Volume 25, No. 11, pp. 1422-1434, November 1954, which is herein incorporated by reference. In an alpha voltaic battery a radioactive substance that emits energetic alpha particles is coupled to a semiconductor p/n junction diode. As the alpha particles penetrate into the p/n junction, they decelerate and give up their energy as electron-hole pairs. These electron-hole pairs are collected by the p/n junction and converted into useful electricity much like a solar cell.
The main reason alpha voltaic batteries are not commercially successful is that the alpha particles damage the semiconductor material so as to degrade its electrical performance in just a matter of hours as disclosed in G. C. Rybicki, C. V. Aburto, R. Uribe, Proceedings of the 25th IEEE Photovoltaic Specialists Conference, pp. 93-96, 1996, which is herein incorporated by reference.